Cathode-ray indicator



March 25, 1952 M. s. MovAY ETAL 2,590,114

CATHODE-RAY INDICATOR Original Filed Mayv 4, 1942 A A l A A A l A l l Al l. v v v v v v y I v y" DIRECTION A A A n A n A A n A.

A l l l .l

SAW-Toom G EN ERATO R SYNcHRoNIzER LSE NER

ANTENNA RoTAT/UN CONTROL SHAFT Millard, s: Mvvay Patented Mar. 25, 1952UNITED STATE' CATHODE-RAY INDICATR Millard S. McVay, Washington, D. C.,and John H. Greig, New York, N. Y.

Continuation of application Serial No. 441,732, May 4, 1942. Thisapplication December 26,

1947, Serial No. 794,074

8 Claims.

This invention relates to indicating systems and more particularly tomeans for facilitating the interpretation of indications produced byradio echo ranging devices or similar apparatuses.

Certain radio echo ranging apparatuses include means for detecting thepresence of all remote objects included within a eld extending 360 aboutthe apparatus, means for determining the range and direction of thedetected objects with respect to the apparatus, and suitable indicatingmeans, such as a cathode ray oscillograph, for providing a visual planrepresentation of the area extending 360 about the apparatus upon whichindications of the detected remote'objects are produced in such a mannerto simultaneously show range and direction thereof.

More particularly, the foregoing types of radio echo ranging apparatusinclude a directional beam antenna supplied with a source of energy forproducing a highly directional beam of energy. The antenna iscontinually rotated in order to scan an area 360 about the apparatuswith such directional energy whereby the energy is reflected from allobjects included within the scanned area. Such apparatuses furtherinclude means for producing a radial sweep on the cathode rayoscillograph which rotates in synchronism with rotation of thedirectional beam antenna so that the radial sweep at all times radiallypropagates in a direction which corresponds to the direction of thesource of energy from the antenna. Means are also provided for receivingreections of the energy from remote objects and for modulating theintensity of the sweep line on the oscillograph whenever reected energyis received. By proper synchronization of the rate of emission of thedirective energy with the rate of propagation of the radial sweep thepositions of reflected energy indications on .the sweep lines are adirect measurement of range of remote objects, while the angularposition of the sweep line at the instant indications appear thereonrepresents the direction of remote objects. In operation of an apparatusof the above type, the intensity of the radial sweep is modulated insuch a manner that only reflected energy indications, which appear assmall arcs, the length of which varies with the range, are only visibleon the oscillograph screen. With an indication of the foregoing type itbecomes extremely diicult to accurately determine the range anddirection of remote objects since reference indications of range anddirection are not provided.

It is therefore an object of the present invention to provide novelmeans for facilitating the (Granted under the act of March 3, 1883, asamended April 30, 1928; 370 0. G. 757) interpretation of indicationsproduced by certain radio echo ranging devices or similar apparatuses.

Another object is to provide a radio echo ranging apparatus having novelindicating means whereby range and direction of remote objects arequickly obtained with a high degree of accuracy.

Still another object of the invention is to provide novel means forfacilitating the determination of range and direction of a pre-selectedreymote object with a high degree of accuracy.

Still another object is to provide a discontinuous circular mark on theoscillograph screen with means for varying the radius of the mark as afunction of range and the angular position of the discontinuous portionof the mark as a function of direction.

Still another object is to provide an indication of vthe foregoingcharacter with novel means for indicating the radius of the circularmark and the angular position of the discontinuous portion thereofrespectively as functions of range and direction.

Other objects and features of the invention will appear more fully fromthe following detailed description when considered in connection withthe accompanying drawing which discloses one embodiment of theinvention. It is to be expressly understood, however, that the drawingis designed for purposes of illustration only and not as a denition ofthe limits of the invention, reference for 'the latter purpose being hadto the appended claims.

In the drawing, wherein similar reference char.- acters denote similarelements throughout the several views: c

Fig. 1 is a diagrammatic showing of a radio echo ranging apparatusembodying the principles of the present invention, and

Fig. 2 is an illustration of the Calibrating mark produced on viewingscreen of the oscillograph disclosed in Fig. 1'. i

With reference more particularly to Fig. 1, a radio echo rangingapparatus is disclosed therein including a rotatable directional beamantenna I0, a cathode ray oscillograph II, a radio frequency pulsetransmitter l2 and a radio frequency pulse receiver I3. Transmitter I2and receiver E3 are connected to antenna Ill through duplexing circuitI4. The duplexing circuit automatically functions to form an individualconnection between transmitter l2 and antenna I0 and an individualconnection between the antenna and receiver I3 so that a single antennamaybe employed for transmission as Well as reception. A duplexingcircuit constructed in accordance with the principles disclosed in thepatent to Wolff, i# 2,401,717, and in the application of Leo C. Youngand Robert M. Page for .impedance Coupling and Decoupling System, SerialNo. 326,640, filed March 1940, adequately serves this purpose. Antennai@ may take the form ci any directional beam antenna capable ofproducing a highly directive beam of energy, while transmitter l2 andreceiver i3 are constructed in such a manner to properly transmit andreceive radio pulses, the types of transmitters and receivers employedin conventional television systems are suitableV for these purposes.Operation of transmitter l2 is controlled by electronic keyer i E insuch a manner that equally Yspaced radio pulses are emitted therefrom atpredetermined rate. Oscillograph il is provided with electro-magneticdeection coils it mounted on anti-friction bearings for rotation aboutthe oscillograph. Deflection coils i3 are wound in such a `nanner toproduce varying magnetic lines of force within the oscillograph, whensaw-tooth varying current is applied thereto, with a source of directcurrent, for deilecting the beam of electrons generated wit in theoscillograph in a radial direction from the center of the oscillograph,upon application of each sawtooth wave forni. Such deection of theelectron beam produces a radial sweep or trace a on viewing screen il ofoscillograph ii. By proper adjustment of bias supply i3 the intensity ofthe electron beam is normally modulated so that the radial sweep d isnot visible. Saw-tooth wave generator iS is provided for applyingsaw-tooth wave forms, as well as a source of direct current, todeiiection coils l through suitable slip rings. Synchronizer 2Q isemployed, with connections to electronic keyer l5 and saw-tooth wavegenerator I9, in order to properly synchronize the pulses emitted fortransmitter i2 with the application of saw-tooth wave forms todeilection coils l5.

Antenna i@ is continuously rotated by means of motor 22, latter beingrotatably connected to the through gear reduction means 23 and shaft 2f.in order to rotate the radial swee a. in synchroniszn with rotation ofantenna ill, deflection coils l@ are rotated by motor 22, through pinion25, and annular gear 26 mounted on the outer periphery of the deflectioncoils. The arrangement is such that the energy emission from antenna iiiand the radial propagation of the electrical beam are at all times inthe same direction. Whenever radio pulses emitted from antenna idinipinge upon remote objects, echo pulses are rcilected from theobjects, passed to receiver i3 wherein such echo pulses are suitablyampliiied an subsequently applied to intensity control grid 2i tomodulate the intensity of the electron beam thus producing visualindication on screen Il.

In'operation of the radio echo ranging apparatus disclosed in `Fig. i,motor 22 continually rotates antenna l and deilection coils itsynchronism. The highly directive beam of energy from antenna iii, whichcomprises radio pulses propagating at a constant rate, is thuscontinually scanned over an area extending 359 about the antenna. Theapplication of saw-tooth varying current from generator i9 to deflectioncoils i6 produces a radial sweep line c on viewing screen il, ofoscillograph il, which rotates in synchronism with rotation of thedirective beam of energy'emitted from the antenna. Synchronizer 2dcontrols operation or electronic .keyer l5 and saw-tooth wave generatori9 in such a manner that a radio pulse is emitted from transmitter I2simultaneously with application oi every saw-tooth wave form todeflection coils i6. Whenever radio pulses emitted from the antennaimpinge upon remote objects, echo pulses are reflected from the objects,received at antenna ID and passed through a channel ci duplexng circuiti4 to receiver I3. The echo pulses are properly amplied by receiver i3and applied to intensity control grid 2l of the oscillograph to modulatethe intensity of the electron beam thereof thus producing an indicationon oscillograph screen Il. Due to operation of synchroniser 2B, suchpulse indications appear at various distances from the center of theoscillograph screen Il in direction proportion to the range of remoteobjects, from which echo pulses are reflected, with respect to antennaill. Since antenna IS] and sweep line c rotate in synchronism, echopulse indications from remote objects appear on oscillograph il atvarious angular positions vthat correspond to the angular position ofremote objects with respect to antenna it.

The foregoing type of radio echo ranging apparatus thus provides avisual plan indication of the area continually scanned by the highlydirective source of energy emitted from antenna IEB, which, in thepresent instance, comprises the viewing screen I1 of the oscillograph.Indications of remote objects are produced on viewing screen l1 in sucha manner that range and direction of all remote objects included withinthe eld scanned by the directive beam of energy from the antenna aresimultaneously shown. In Fig. l, indications of remote objects,designated by b, are shown on viewing screen l1, at various radialdistances from the center of the oscillograph screen and at differentangular positions thereon. Indications b represent positions of remoteobjects with respect to antenna lil; the angular positions of theindications, with respect to the center of viewing screen Il, representdirections of such remote objects with respect to antenna I0, while theradial distance of the indications from the center of screen ilcorrespond to the range of remote objects with respect to the antenna.As mentioned heretofore, bias supply i9 is adjusted in such a manner asto modulate the intensity of the electron beam of oscillograph il sothat sweep line a is not visible; therefore, remote object indications bare only visible on screen Il.

As mentioned heretofore, means are provided by the present invention forfacilitating the interpretation of remote object indications b wherebyrange and direction of remote objects are quickly obtained therefromwith a high degree of accuracy, as well as for readily determining andindicating the range and direction of a pre-selected remote object witha high degree of accuracy, and means for continually and accuratelyindicating vari-ations in range and direction of a pre-selected remoteobject. It is contemplated by the present invention to produce adiscontinuous circular mark on the viewing screen of the oscillograph,symmetrical with respect to the center of the screen, with means forvarying and indicating the radius of the circular mark as a function ofrange, as well as means for angularly varying and indicating theposition of the discontinuous portion of the mark as a function ofdirection. With the foregoing arrangement, by proper variations of theradius of :the'circular markand theangular position of the discontinuousportion thereof, the circular mark may be moved to a position wherein aremote object b is symmetrically positioned within the discontinuousportion. Range and direction of the remote object represented by theindication b is thus directly obtained from suitable indicating meansassociated with the apparatus. When the range and direction of theremote object varies, the radius and angular position of thediscontinuous circular mark is varied to maintain the remote objectindication symmetrically positioned within the discontinuous portionwhereby continuous indications of range and direction are provided.

1n order to produce a calibrating mark of the foregoing character novelmeans are provided by the present invention for generating a positiveimpulse which is applied to intensity control grid 2| of oscillographll. The generation of such impulses are properly synchronized with theradial propagation of the electron beam, as well as with the rate ofpulse generation at transmitter l2, in order to provide indications onscreen i1 of a certain range calibration which corresponds to the rangecalibration of sweep line a. The positive impulses are applied tointensity control grid 2| in synchronism with application of saw-toothcurrent wave forms to deflection coils I6 for a substantially largeperiod of time during each complete revolution of the radiallypropagating electron beam to thus produce a discontinuous circle onscreen I1 upon each coni.- plete revolution of antenna I3.

4./is shown in Fig. 1, the device for generating a positive impulseduring the period of each radial propagation of the electron beamincludes vacuum tube 30 which is triggered upon application of apositive impulse to the grid thereof from electronic keyer l5simultaneously with generation of a pulse at transmitter I2. Tube 3|)thus generates a negative impulse which is applied to the control gridof vacuum tube 3|. Tube 3| is interconnected with vacuum tube 32 to forma multi-vibrator circuit which comprises a twostage capacitance coupledamplifier with regenerative feedback. When a negative impulse is appliedto the control grid of tube 3|, the tube is blocked, thus applying apositive bias to the control grid of tube 32, rendering the latter tubeconducting and producing a potential drop at the plate thereof. Theplate of tube 32 remains at a low potential for a period of timedetermined by the values of grid resistances 33, 33 and capacitances 34,34 associated with the control grids of tubes 3| and32. output of tube32 is applied to the control grid of vacuum tube 35. Tube 35 is normallymaintained in a conducting state by proper selection of plate resistors36 and grid resistor 31 and is blocked upon application of a negativeimpulse to the control grid thereof. Capacitance 38 is connected acrossthe plate and cathode of tube 35 and charges exponentially throughresistor 35 when tube 35 is in a non-conducting state. The exponentiallyincreasing potential of capacitance 38 is applied through a winding oftransformer 49 to the control grid of tube 4i. Tube 4| is normallymaintained in a non-conducting state and the cut-olf potential thereofis varied by means of potentiometer 42 in order to determine the timethat tube 4| is rendered conducting following the instant capacitance 38commences to charge exponentially. For a purpose that will appear morefully hereinafter, potentiometer 42 is adjustable upon manual rotationof dial 43.

The negative impulse Transformer 4|]` has connections with the plate andcontrol grid of tube 4| in order tofunction as an oscillating circuit;however, such circuit is suitably damped by resistances 44 and 45 tolimit the extent of oscillatory actiontherein. When the exponentiallyincreasing charge of capacitance 38 reaches a suicient value to rendertube 4| conducting, a negative impulse is generated at the outputthereof, and oscillations commence in the oscillatory circuit betweenthe plate and control grid of the tube. Resistances 44 and 45, however,damp such oscillations to only allow generation of a single positiveimpulse following generation of the negative impulse. The output of tube4| is connected through condenser 46 to the control grid of amplier tube41 which is normally biased in a conducting state. When the negativeimpulse output of tube 4| is applied tothe control grid of tube 41 thelatter tube-is blocked for an interval of time determined by theduration of the negative impulse, during which time a positive impulseis generated at the output of tube 41. The amplitude of the positiveimpulse generated at the output of tube 41 is controlled by adjustmentof potentiometer device 48. The output of tube 4| is also appliedthrough condenser 49 to the control grid of vacuum tube 53 to re-set themulti-vibrator. When the positive impulse from tube 4| is applied to thegrid of tube 58, the tube draws current thus producing a drop inpotential at the grid of tube 32, blocking the latter tube. Tube 3| isdriven conducting, and the multi-vibrator is thus re-set to a conditionresponsive to application of the next negative impulse from tube 30.

The positive pulse output of tube 41 is applied to intensity controlgrid 2| to modulate the intensity of the electron beam at a certaininstant during every radial propagation of the electron beam. In orderto prevent application of the positive impulses during a certain periodof each complete revolution of the radial propagating electron beam tothus produce a discontinuous circular mark on screen |1, suitableswitching means are provided for controlling application of the positiveimpulses to grid 2|. Such means comprises a cylindrical member 60, ofinsulating material, rotatably mounted on shaft 24 for synchronousrotation with antenna I0. A discontinuous circular metallic conductor 6|is imbedded in the outer periphery of member 6U and is electricallyconnected through suitable slip rings, not shown, to the output of tube41 by way of electrical conductor 62. Stationary contact |33 is mountedon angular ring 64 and is electrically connected to intensity controlgrid 2|. With the foregoing arrangement, the positive impulse output oftube 41 is applied to intensity control grid 2| only during the timewhen electrical contact is maintained between conductor 6i andstationary contact 63. Since conductor 6| contacts stationary contact E3for a greater period during each revolution of shaft 24 the output oftube 41 is applied to intensity control grid 2| during a greater portionof each complete revolution of shaft 24. A discontinuous circularcalibration mark is thus produced on screen |1 for each completerevolution of antenna I0. The angulaiportion of the discontinuousportion thereof is determined by the angular position of stationarycontact 63. Annular member 64 is provided with an annular gear 65, 0nthe outer periphery thereof, which cooperates with pinion 66 whereby theannular position of stationary contact B3 is varied upon manual rotationof pinion 66 through control dial vtl to vary the angular position ofthe discontinuous portion of the circular mark.

As mentioned heretofore, since the range of remote objects is determinedby the radial distance of indications b from the center of the screenil, and since the direction of such objects is determined from theangular position of the indications, the novel arrangement disclosedherein provides means for determining the range and direction of remoteobjects from such indications With a high degree of accuracy.Capacitances 38, as well as the circuit constants associated therewith,are selected so that the rate oi exponential charge on the capacitancecorresponds to the linearly increasing portion of the saw-tooth Waveforms applied to deflection coils I6, and is therefore, at all times,equal to the rate of radial propagation of the electron beam of theoscillograph. The pulses produced at the output of tube 4l, andconsequently the discontinuous circular mark produced on screen Il, istherefore synchronously calibrated in range with the remote objectindications b. Since the time of generation of the pulse output of tube41, following initiation of the radial scanning of the electron beam, isvaried upon operation of potentiometer 42, through dial 43, dial i3 iscalibrated in range so that the radial positions of the positive pulse,with respect to the radial scanning time of the electron beam, isdetermined as a function of range from dial 43. Moreover, since member60 rotates in synchronism with rotation of antenna It, dial 6l iscalibrated in degrees so that various angular positions of thediscontinuous portion of the circular mark on screen l1 are accuratelydetermined therefrom.

When utilizing a device having the foregoing characteristics foraccurately determining range and direction of a remote object from anindication b on screen il, dial 43 is operated to vary the radius of thediscontinuous concentric calibration mark in order to coincide with theradial distance of the indication, while dial 61 is rotated to angularlyvary the position of the discontinuous portion until the remote objectindication b is symmetrically located within such portion, as shown inFig. 2 of the drawing. The range and direction of the remote objectcorresponding to such indication is then directly read from dials t3 and61 with a high degree of accuracy. Variations in range and direction ofthe remote object is readily obtained by proper operation of dials 43and 67 to maintain a remote object indication b symmetrically within thediscontinuous portion of the circular mark.

There is thus provided by the present invention novel means forfacilitating the interpretation of indications produced by radio echoranging devices or similar apparatuses of the type disclosed herein.Means are provided by the present invention for producing directindications of range and direction of a remote object from theindication thereof produced on the indicator of the apparatus. Suchmeans is capable of producing continuous indications of range anddirection of a pre-selected remote object, with a high degree ofaccuracy, when such object varies in range and direction to any positionabout the apparatus.

Although one embodiment of the present invention has been disclosed anddescribed herein, it is to be expressly understood that various changesand substitutions may be made therein without departing from the spiritof the invention as well understood by those skilled in the art.Reference therefor will be had to the appended claims for a definitionof the limits of the invention.

This application is a continuation of application Serial Number 441,732,nled May li, 1942, and now abandoned.

The invention described herein may be manuiactured and used by or forthe Government of the United States of America for govemmental purposeswithout the payment of any royalties thereon or therefor.

What is claimed is:

l. A cathode ray indicator comprising a cathode ray tube having meansfor generating a beam and an indicator screen for receiving the beam,sweep means for defiecting the beam radially of the screen, sweepcontrol means operative to control the direction of the radial sweep,beam control signal generator means operative to modulate the beamintensity to provide a reference indication on the radial sweep, andvariable time delay means becoming operative in definite time relationwith the sweep means to initiate operation of the signal generator meansto provide a reference indication on the radial sweep.

2. A cathode ray indicator comprising a cathode ray tube having meansfor generating a beam and an indicator screen for receiving the beam,sweep means for deiiecting the beam radially of the screen, sweepinitiating means for initiating operation of the sweep means, signalgenerator means operative to modulate the beam intensity, variable timedelay control means becoming operative synchronously with the sweepinitiating means to initiate operation of the signal generator in denitetime relation with the sweep after Ia selected time delay interval, andmeans for controlling the direction of the radial sweep.

3. A cathode ray indicator comprising a cathode ray tube having meansfor generating a beam and an indicator screen for receiving the beam,sweep means for deilecting the beam radially of the screen, rotatablesweep control means operative to control the direction of the radialsweep, beam modulation means, and signal generator means feeding thebeam modulation means at an adjustably selectable position of therotatable sweep control means to modulate the beam.

4. A cathode ray indicator comprising a cathode ray tube having meansfor generating a beam and an indicator screen for receiving the beam,sweep means for delecting the beam radially of the screen, continuouslyoperative rotatable sweep control means for rotating the direction ofthe radial sweep, beam modulation means, signal generator means forfeeding the beam modulation means, and control means for the signalgenerator' means operative synchronously with the rotatable sweepcontrol means to eiect application of the signal generator output to thebeam modulation means at an adjustably selectable position or" the sweepcontrol means.

5. A cathode ray indicator comprising a cathode ray tube having meansfor generating a beam and an indicator screen for receiving the beam,rmeans for sweeping the beam radially of the indicator screen in a locusprogressively advancing around the screen and beam modulation meansoperative to establish a reference indication on the indicator screen atan adjustably selectable radial position thereon.

6. A cathode ray indicator comprising a cathode ray tube having meansfor generating a beam and an indicator screen for receiving the beam,means for sweeping the beam radially of the indicator screen in a locusprogressively ad- Vancing around the screen, and beam modulation meansoperative to effect the application of a reference indication at anadjustably selectable orientation of the radial sweep.

7. A cathode ray indicator comprising a cathode ray tube having meansfor generating a beam and an indicator screen for receiving the beam,means for sweeping the beam radially of the indicator screen in a locusprogressively advancing around the screen, and beam modulation meansoperative to eiiect the application of a reference indication at anadjustably selectable radial position and an adjustaloly selectableradial direction on the screen.

8. A cathode ray indicator comprising a cathode ray tube having meansfor generating a beam and an indicator screen for receiving the beam,means for recurrentlysnweeping the beam over adjacent trace lines todefine a two-dimensional sweep area on the screen, and adjustable l0beam modulation means operative to establish a reference indication inany selected portion of the sweep area.

MILLARD S. MCVAY. JOHN H. GREIG.

REFERENCES CITED The following references are of record in the tile ofthis patent:

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